Prosthetic device with damper

ABSTRACT

A prosthetic joint assembly supports articulation of a joint. The joint assembly includes a first component configured to be fixed to an anatomical feature. The first component includes a first impact surface and a second component that engages the first component. The second component includes a second impact surface that impacts the first impact surface as the first component moves relative to the second component. Furthermore, at least one of the first impact surface and the second impact surface includes a dampening member that dampens energy resulting from impact of the first and second impact surfaces.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/531,737 filed on Jun. 25, 2012, which is a divisional of U.S. patentapplication Ser. No. 12/708,247 filed on Feb. 18, 2010, now U.S. Pat.No. 8,206,452 issued on Jun. 26, 2012. The entire disclosures of theabove applications are incorporated herein by reference.

FIELD

The following relates to a prosthetic device and, more particularly, toa prosthetic device with a damper.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Prosthetic joints can reduce pain due to arthritis, deterioration,deformation, and the like, and can improve mobility of the joint.Oftentimes, prosthetic joints can include certain implantable prostheticmembers that are fixed to the patient's anatomy. For instance, kneejoint prosthetic devices can include a femoral component fixed to thepatient's femur and a tibial component fixed to the patient's tibia.Also, the device can include a bearing disposed between the femoral andtibial components. The bearing can be supported by the tibial component,and the bearing can include a bearing surface. An articulating surfaceof the femoral component can articulate on the bearing surface of thebearing.

In some cases, these components can include surfaces that impact eachother during articulation of the joint. For instance, in someembodiments, surfaces of the femoral component can impact surfaces ofthe bearing when the femoral component moves relative to the bearing.Also, in some embodiments, surfaces of the bearing can impact surfacesof the tibial component when the bearing moves relative to the tibialcomponent.

SUMMARY

A prosthetic joint assembly is disclosed that supports articulation of ajoint. The joint assembly includes a first component configured to befixed to an anatomical feature. The first component includes a firstimpact surface and a second component that engages the first component.The second component includes a second impact surface that impacts thefirst impact surface as the first component moves relative to the secondcomponent. Furthermore, at least one of the first impact surface and thesecond impact surface includes a dampening member that dampens energyresulting from impact of the first and second impact surfaces.

A method of implanting a prosthetic joint assembly into a patient isalso disclosed. The method includes fixing a first component of theprosthetic joint assembly to an anatomical feature. The first componentincludes a first impact surface. Moreover, the method includessupporting a second component of the prosthetic knee assembly formovement relative to the first component such that a second impactsurface of the second component impacts the first impact surface of thefirst component as the second component moves relative to the firstcomponent. At least one of the first impact surface and the secondimpact surface includes a dampening member that dampens energy resultingfrom impact of the first and second impact surfaces.

Moreover, a prosthetic knee assembly for supporting articulation of aknee joint is disclosed. The knee assembly includes a femoral componenthaving an articulating surface and a tibial component having a tray anda projection that extends in a superior direction from the tray. Thebearing is movably supported on the tray, and the bearing includes abearing surface that supports the articulating surface for articulationthereon. The bearing also includes an aperture with an inner surface,and the aperture receives the projection of the tibial component formovement therein. At least one of the projection and the inner surfaceof the aperture includes a hollow, tubular sound dampening member thatdampens noise resulting from impact of the bearing and the tibialcomponent.

Still further, a prosthetic knee assembly for supporting articulation ofa knee joint is disclosed. The knee assembly includes a tibial componentand a femoral component having an articulating surface and a cam. Thecam includes a cam surface. Furthermore, the knee assembly includes abearing fixed to the tray. The bearing includes a bearing surface thatsupports the articulating surface for articulation thereon. The bearingalso includes a projection that extends in a superior direction awayfrom the bearing surface. The cam cams against the projection to cam thefemoral component relative to the bearing. Moreover, at least one of thecam surface and the projection surface includes a sound dampening memberthat dampens noise resulting from impact of the bearing and the femoralcomponent.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is an exploded, posterior view of a prosthetic joint assemblyaccording to various exemplary embodiments of the present disclosure;

FIG. 2 is a sectional view of the prosthetic joint assembly in anassembled state that is taken along the line 2-2 of FIG. 1;

FIGS. 3 and 4 are sectional views of the prosthetic joint assembly ofFIG. 2, each shown in different stages of articulation;

FIG. 5 is an exploded view of a prosthetic joint assembly according tofurther exemplary embodiments of the present disclosure; and

FIG. 6 is a top view of the prosthetic joint assembly of FIG. 5.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

Referring initially to FIG. 1, a prosthetic joint assembly 10 isillustrated according to various exemplary embodiments of the presentdisclosure. The assembly 10 can be a knee joint assembly 12 forsupporting articulation of a knee joint; however, the assembly 10 can befor any joint other than a knee joint without departing from the scopeof the present disclosure.

As shown, the knee joint assembly 12 can be secured to a femur 14 and atibia 16 of a surgically resected left knee joint (the femur 14 and thetibia 16 shown in phantom). It will be understood that while the kneejoint assembly 12 can be implanted into a left knee joint, the kneejoint assembly 12 can be configured for implantation into a right kneejoint. It will also be appreciated that the knee joint assembly 12 canbe configured as a cruciate retaining (CR) joint assembly, a posteriorstabilized (PS) joint assembly, a fully constrained joint assembly, ahinged knee joint assembly, or any other suitable knee joint assembly12.

Specifically, the knee joint assembly 12 can include a femoral component18 that can be secured to the distal end of the femur 14 after the femur14 has been resected in a manner well known in the art. The femoralcomponent 18 can be fixed to the femur 14 via fasteners, bone cement,and/or any other suitable means. Also, the femoral component 18 can beunitary and monolithic in structure and can be made from any suitablebiocompatible material.

The femoral component 18 can include a stem 20, which can be tubular inshape and can be received and fixed in a bore (not specifically shown)formed in the resected femur 14. The femoral component 18 can alsoinclude a patellar track 21, a posterior portion 23, and a plurality ofcondyles 24, 26, which are spaced apart in the medial-lateral directionto define an intercondylar box 25. Moreover, the femoral component 18can include a bone engaging surface 22 (FIGS. 2-4).

The bone engaging surface 22 (FIGS. 2-4) can include one or more planarand/or curved surfaces that engage and fit to corresponding surfaces ofthe resected femur 14. The condyles 24, 26 can be opposite the boneengaging surface 22 and can include a first condyle 24 and a secondcondyle 26. The first and second condyles 24, 26 can have a shapesubstantially similar to anatomical condyles of a femur 14. The firstcondyle 24 can include a first articulating surface 28, and the secondcondyle 26 can include a second articulating surface 30 (FIG. 1). Thefirst and second articulating surfaces 28, 30 can be polished so as toprovide a substantially smooth surface for supporting articulation ofthe knee joint assembly 12.

The intercondylar box 25 can define an intercondylar recess 32 and a cam34 (FIGS. 2-4). The cam 34 can be disposed in a posterior directionrelative to the recess 32. The cam 34 can be bulbous and continuous inshape so as to include an anterior surface 36 (FIGS. 2-4) that faces therecess 32 and an inferior surface 38 (FIGS. 2-4). As will be discussedin greater detail below, the cam 34 can provide guided, camming movementof the femoral component 18 relative to other portions of the knee jointassembly 12.

Furthermore, the knee joint assembly 12 can include a tibial component40 that can be fixed to a superior end of the resected tibia 16. Thetibial component 40 can be fixed to the tibia 16 via fasteners, bonecement, and/or any other suitable means. The tibial component 40 can beunitary and monolithic and can be made of any suitable biocompatiblematerial.

Generally, the tibial component 40 can include a stem 42 and tray 44.The stem 42 can be tubular and can be received and fixed in a bore (notspecifically shown) formed in the resected tibia 16. The tray 44 can besubstantially flat and can include a bone engaging surface 46 thatengages the superior end of the resected tibia 16 and a superior surface48 that is opposite the bone engaging surface 46. The bone engagingsurface 46 can be porous, coated, or otherwise surface treated in amanner that promotes bone growth and attachment to the bone engagingsurface 46. The tibial component 40 can further include a pair ofintegrally formed posts 50, 52 (FIG. 1), which extend superiorly from aposterior edge of the tray 44 (FIGS. 2-3). The posts 50, 52 can bespaced apart equally from a center of the tray 44. The posts 50, 52 caneach include a posterior flange 54 (shown in phantom in FIG. 1). Thetray 44 can also include an anterior projection 56 (FIG. 1) that extendssuperiorly from the anterior portion of the tray 44. The anteriorprojection 56 can include a channel 58.

Additionally, the knee joint assembly 12 can include a bearing 60. Thebearing 60 can be a unitary, monolithic material made out of anysuitable biocompatible material, such as polyethylene (e.g., ultra-highmolecular weight polyethylene (UHMWPE), cross linked polyethylene,vitamin-E infused polyethylene, etc.) As shown in FIGS. 2-4, the bearing60 can include an anterior portion 62, a posterior portion 64, aninferior surface 66, and a superior surface 68. As will be discussed ingreater detail, the bearing 60 can engage both the femoral component 18and the tibial component 40, and the bearing 60 can support articulationof the knee joint assembly 12.

The inferior surface 66 can be substantially flat and can be supporteddirectly on the superior surface 48 of the tibial component 40.Moreover, the bearing 60 can include a posterior flange 70 (FIG. 1) andan anterior groove 71 (FIG. 2). A pin 72 can be received in the anteriorgroove 71 and the anterior groove 58 of the tibial component 40 (FIGS. 2and 3) in order to fix the bearing 60 to the tibial component 40.Moreover, the posterior flange 70 can engage the posterior flange 54 ofthe tibial tray 44 (not specifically shown) in order to further securethe bearing 60 to the tibial component 40.

Moreover, the superior surface 68 of the bearing 60 can include a firstbearing surface 73 and a second bearing surface 74 (FIG. 1), which caneach have a three-dimensional concave curvature. The first bearingsurface 73 can support the first articulating surface 28 forarticulation thereon, and the second bearing surface 74 can support thesecond articulating surface 30 for articulation thereon. As such, thebearing surfaces 73, 74 can support articulation of the knee jointassembly 12 as the femoral component 18 moves relative to the bearing 60and the tibial component 40.

In addition, the superior surface 68 of the bearing 60 can include aprojection 76 (i.e., posterior-stabilizing post) that is disposedbetween and extends superiorly away from the first and second bearingsurfaces 73, 74. As shown in FIGS. 1-4, the projection 76 can besubstantially cubic in shape. As such, the projection 76 can include asuperior surface 78, an anterior surface 80, and a posterior surface 82.The projection 76 can be sized and shaped so as to be received withinthe intercondylar recess 32 of the femoral component 18. Also, as willbe discussed in greater detail, the cam 34 of the femoral component 18can cam against the projection 76 to provide camming motion of thebearing 60 relative to the femoral component 18. During such movement,the cam 34 can impact the projection 76. More specifically, at certainpositions of the femoral component 18 relative to the bearing 60 (e.g.,FIG. 2), the cam 34 and projection 76 can be spaced apart, and duringarticulation of the joint (e.g., FIG. 3), the cam 34 and projection 76can move toward each other to initially impact. Thus, the cam 34 andprojection 76 can each define impacting surfaces as will be discussed ingreater detail.

At least one of the impacting surfaces of the cam 34 and the projection76 can include a dampening member 84 a, 84 b. For instance, the kneejoint assembly 12 can include a first dampening member 84 a and a seconddampening member 84 b (FIGS. 2-4). As will be discussed, the dampeningmembers 84 a, 84 b can be disposed between the projection 76 of thebearing 60 and the cam 34 of the femoral component 18 to dampen energythat results when the femoral component 18 impacts the bearing 60. Morespecifically, the dampening members 84 a, 84 b can cushion the impact ofthe femoral component 18 and the bearing 60, and the dampening members84 a, 84 b can dampen, reduce, and dissipate various forms of impactenergy, such as audible noise, vibrations, shock impulse, kineticenergy, and the like, resulting from impact of the femoral component 18and the bearing 60. For instance, sound that would otherwise occur ifthe femoral component 18 and the bearing 60 were to directly contact canbe substantially reduced by the dampening members 84 a, 84 b.Accordingly, the knee joint assembly 12 can be less noticeable to thepatient while the knee joint assembly 12 articulates.

For purposes of discussion, the dampening members 84 a, 84 b will bediscussed primarily as reducing, damping, and dissipating impact sound,noise, and vibration. However, it will be appreciated that the dampeningmembers 84 a, 84 b can reduce, dampen, and dissipate any other impacteffects without departing from the scope of the present disclosure.

The dampening members 84 a can be made out of a material having a lowerstiffness and/or lower hardness than other portions of the bearing 60(e.g., the bearing surfaces 73, 74). For instance, in some exemplaryembodiments, the dampening member 84 a can be made out of polyurethane(e.g., BIONATE polyurethane or other similar biocompatiblepolyurethane). Assuming the rest of the bearing 60 is made frompolyethylene, the dampening member 84 a can be an order of magnitudeless stiff and approximately half as hard as the other portions of thebearing 60. The dampening member 84 b can be made out of a materialsimilar to the dampening member 84 a.

The dampening members 84 a, 84 b can be disposed at any suitablelocation on the femoral component 18 and/or the bearing 60 whereengagement or impact occurs (i.e., located on impacting surfaces of thefemoral component 18 and/or the bearing 60). For instance, as shown inFIGS. 2-4, the first dampening member 84 a can be disposed on and candefine at least a portion of the superior surface 78 and the posteriorsurface 82 of the projection 76 of the bearing 60. Also, the seconddampening member 84 b can be disposed on and can define at least aportion of the anterior surface 36 and inferior surface 38 of the cam 34of the femoral component 18. However, it will be appreciated that thedampening members 84 a, 84 b can be disposed between any surfaces of thebearing 60 and the femoral component 18 that would otherwise impact,abut, and/or make noise.

It will also be appreciated that the knee joint assembly 12 can includeonly one of the first and second dampening members 84 a, 84 b withoutdeparting from the scope of the present disclosure. As such, the kneejoint assembly 12 can include only the first dampening member 84 a.Also, the knee joint assembly 12 can include only the second dampeningmember 84 b.

The first dampening member 84 a can be fixed to the bearing 60 in anysuitable fashion. The first dampening member 84 a can be integrallycoupled or removably coupled to the projection 76 of the bearing 60. Forinstance, the first dampening member 84 a can be insert molded orotherwise molded to the projection 76, fixed by adhesives, fasteners,etc. The second dampening member 84 b can be fixed to the cam 34 in asimilar fashion.

Exemplary embodiments of articulation of the knee joint assembly 12 willnow be discussed in greater detail. When in the position shown in FIG.2, the articulating surfaces 28, 30 of the femoral component 18 can beslidingly supported on the bearing surfaces 73, 74 of the bearing 60. Asthe knee joint assembly 12 articulates, the articulating surfaces 28, 30can continue to slide and articulate on the bearing surfaces 73, 74.Also, as the knee joint assembly 12 articulates away from the positionof FIG. 2 and towards the positions of FIGS. 3 and 4, the cam 34 can camagainst the projection 76. More specifically, the shape of the cam 34causes the cam 34 to cammingly push against the projection 76 such thatthe bearing 60 and the tibial component 40 move in an anterior directionrelative to the femoral component 18.

In addition, when the knee joint assembly 12 is in the position shown inFIG. 2, the cam 34 and the second dampening member 84 b can be spacedapart from the projection 76 and the dampening member 84 a. However, asthe joint assembly 12 moves toward the position shown in FIG. 3, thesecond dampening member 84 b can contact the first dampening member 84 aand the cam 34 can impact the projection 76. Because of the relativelylow stiffness and/or harness of the dampening members 84 a, 84 b, soundof such impact can be significantly reduced. Accordingly, articulationof the joint assembly 12 can be advantageously less noticeable, andpotentially annoying clicking or popping noises are unlikely.

As stated above, the knee joint assembly 12 can include only one of thefirst and second dampening members 84 a, 84 b. For instance, when theknee joint assembly 12 includes the first dampening member 84 a, thefirst dampening member 84 a can directly contact the cam 34 duringarticulation of the knee joint assembly 12. Likewise, when the kneejoint assembly 12 includes the second dampening member 84 b, the seconddampening member 84 b can directly contact the projection 76. In eithercase, sounds caused by impact of these features can be significantlyreduced.

Referring now to FIGS. 5 and 6, further exemplary embodiments of theprosthetic knee joint assembly 112 are illustrated. Components that aresimilar to the embodiments of FIGS. 1-4 are indicated with similarreference numerals increased by 100.

As shown, the assembly 112 can include a tibial component 140 and abearing 160. Although not shown, the assembly 112 can also include afemoral component of the type discussed above. As will be discussed, thebearing 160 can be supported for movement relative to the tibialcomponent 140. This relative movement of the bearing 160 can allow forimproved mobility of the assembly 112 as discussed in U.S. Pat. No.6,972,039, filed Jul. 1, 2002, to Metzger et al., the disclosure ofwhich is hereby incorporated by reference in its entirety.

The tibial component 140 can include a stem 142 and a tray 144. Thetibial component 140 can also include a projection 143 that extendssuperiorly from the tray 144 on a side of the tray 144 opposite from thestem 142. The projection 143 can be tubular and can include an outersurface 145. Also, in some embodiments, the projection 143 (e.g., guidepost) can be removably coupled to the tray 144 and/or stem 142 of thetibial component 140.

Moreover, the bearing 160 can include an aperture 163 (e.g., throughhole) that extends between the inferior and superior surfaces 166, 168of the bearing 160. As shown in FIG. 6, the aperture 163 can be a slotthat extends in the anterior/posterior direction as represented by thevertical double headed arrows in FIG. 6. The projection 143 can bemovably received in the aperture 163 to allow the bearing 160 to move inthe anterior/posterior direction relative to the tibial component 140.However, it will be appreciated that the aperture 163 can be of anysuitable shape to allow any relative movement of the bearing 160 andtibial component 140. For instance, the aperture 163 can have a curvedaxis to allow rotation of the bearing 160 relative to the tibialcomponent 140 about the projection 143. Furthermore, in someembodiments, the aperture 163 can have a shape that allows both linearmovement and rotational movement of the bearing 160 relative to thetibial component 140.

The assembly 112 can also include a first dampening member 184 a and asecond dampening member 184 b. The first and second dampening members184 a, 184 b can each be ring-shaped (i.e., tubular and hollow). Assuch, the first dampening member 184 a can include an inner surface 191and an outer surface 193, and the second dampening member 184 b caninclude an inner surface 195 and an outer surface 197. However, it willbe appreciated that the first and second dampening members 184 a, 184 bcan have any suitable shape.

Also, the first and second dampening members 184 a, 184 b can bedisposed between the bearing 160 and the tibial component 140. Forinstance, the inner surface 191 of the first dampening member 184 a canbe fixed to the outer surface 145 of the projection 143, and the firstdampening member 184 a can enclose the projection 143. Also, the outersurface 197 of the second dampening member 184 b can be fixed to theinner surface 161 of the bearing 160, and the bearing 160 can enclosethe second dampening member 184 b. In some embodiments, the first andsecond dampening members 184 a, 184 b can be molded, adhesivelyattached, or otherwise fixed to the projection 143 and the bearing 160,respectively. In other embodiments, the dampening members 184 a, 184 bcan be removably coupled, such as via an interference fit, to theprojection 143 and bearing 160, respectively.

As shown in FIG. 6, the projection 143 and the first dampening member184 a can be movably received in the second dampening member 184 b andthe aperture 163. Accordingly, the bearing 160 can move relative to thetibial component 140, and the projection 143 can impact the bearing 160to limit this relative motion. Also, the dampening members 184 a, 184 bcan absorb the force and reduce the sound of such impact. Accordingly,the prosthetic knee joint assembly 112 is less noticeable during use.

Moreover, the knee joint assembly 112 can include only one of the firstand second dampening members 184 a, 184 b. If only one of the dampeningmembers 184 a, 184 b is included, sound of impact can be significantlyreduced.

Moreover, the foregoing discussion discloses and describes merelyexemplary embodiments of the present disclosure. One skilled in the artwill readily recognize from such discussion, and from the accompanyingdrawings and claims, that various changes, modifications and variationsmay be made therein without departing from the spirit and scope of thedisclosure as defined in the following claims. For instance, thesequence of the blocks of the method described herein can be changedwithout departing from the scope of the present disclosure.

What is claimed is:
 1. A prosthetic knee joint assembly for supportingarticulation of a knee joint, comprising: a femoral component configuredto be fixed to a femur and having an articulating surface; a tibialcomponent configured to be fixed to a tibia; a bearing having a bearingsurface and positioned atop the tibial component, the articulatingsurface of the femoral component supported for articulation on thebearing surface of the bearing; a projection extending superiorly andhaving a first dampening member having a first impact surface; and asecond dampening member having a second impact surface; wherein thefirst and second dampening members are configured to dampen energyresulting from impact of the first and second impact surfaces uponarticulation of the knee joint assembly; and wherein the first andsecond dampening members have at least one of a lower stiffness and alower hardness than the bearing surface.
 2. The prosthetic knee jointassembly of claim 1, wherein the tibial component includes a tibial trayand an inferiorly extending stem, the projection extending superiorlyrelative to the tibial tray.
 3. The prosthetic knee joint assembly ofclaim 2, wherein the projection forms part of the bearing and extendssuperiorly into a recess defined in the femoral component.
 4. Theprosthetic knee joint assembly of claim 3, wherein the femoral componentfurther includes a cam positioned within the recess and the seconddampening member is attached to at least a portion of the cam.
 5. Theprosthetic knee joint assembly of claim 4, wherein the first dampeningmember is attached on a posterior portion of the projection and thesecond dampening member is attached to an anterior portion of the cam.6. The prosthetic knee joint assembly of claim 5, wherein the bearing isfixedly coupled to the tibial tray.
 7. The prosthetic knee jointassembly of claim 2, wherein the bearing defines an aperture extendinginferiorly and superiorly through the bearing and the aperture isconfigured to receive the superiorly extending projection that isfixedly attached to the tibial tray.
 8. The prosthetic knee jointassembly of claim 7, wherein the second dampening member is positionedwithin the aperture of the bearing and is configured to engage the firstdampening member extending from the projection.
 9. The prosthetic kneejoint assembly of claim 8, wherein the aperture is an elongated slotconfigured to enable the bearing to move relative to the tibial tray.10. The prosthetic knee joint assembly of claim 8, wherein the firstdampening member is tubular and hollow and receives the projection andthe second dampening member is tubular and hollow and receives the firstdampening member and the projection.
 11. The prosthetic knee jointassembly of claim 1, wherein the first and second dampening members haveat least one of a lower stiffness and a lower hardness than thearticulating surface of the femoral component.
 12. The prosthetic kneejoint assembly of claim 1, wherein the first dampening member and thesecond dampening member are formed of polyurethane.
 13. A prostheticknee joint assembly for supporting articulation of a knee joint,comprising: a femoral component configured to be fixed to a femur andhaving a first condyle having a first articulating surface and a secondcondyle having a second articulating surface; a tibial componentconfigured to be fixed to a tibia and having a tibial tray and aninferiorly extending stem; a bearing having a first bearing surface anda second bearing surface and positioned atop the tibial tray, the firstand second articulating surfaces of the femoral component supported forarticulation on the first and second bearing surfaces of the bearing,respectively; a projection extending superiorly relative to the tibialtray and having a first dampening member having a first impact surface;and a second dampening member having a second impact surface andconfigured to engage the first dampening member upon articulation of theknee joint assembly; wherein the first and second dampening members areconfigured to dampen energy resulting from impact of the first andsecond impact surfaces; and wherein the first and second dampeningmembers have at least one of a lower stiffness and a lower hardness thanthe first and second bearing surfaces.
 14. The prosthetic knee jointassembly of claim 13, wherein the bearing is fixed relative to thetibial component and the projection forms part of the bearing thatextends between the first and second condyles.
 15. The prosthetic kneejoint assembly of claim 14, wherein the second dampening member isattached to a cam in an intercondylar box of the femoral componentbetween the first condyle and the second condyle.
 16. The prostheticknee joint assembly of claim 13, wherein the first and second dampeningmembers have at least one of a lower stiffness and a lower hardness thanthe first and second articulating surfaces.
 17. The prosthetic kneejoint assembly of claim 13, wherein the bearing defines an aperture andthe projection extends superiorly within the aperture and the bearing ismovable relative to the tibial component.
 18. The prosthetic knee jointassembly of claim 17, wherein the second dampening member is positionedwithin the aperture of the bearing for engagement with the firstdampening member on the projection.
 19. The prosthetic knee jointassembly of claim 18, wherein the first dampening member is disposedbetween an inner surface of the aperture and the projection and thesecond dampening member is disposed within the aperture of the bearingand in contact with the inner surface.
 20. A method of dampening aprosthetic knee joint assembly, comprising: implanting a first kneejoint component having a bearing surface and a first dampening memberhaving a first impact surface; implanting a second knee joint componenthaving a second dampening member having a second impact surface; whereinthe first and second dampening members have at least one of a lowerstiffness and a lower hardness than the bearing surface; and wherein thefirst and second dampening members are configured to dampen energyresulting from impact of the first and second impact surfaces duringarticulation of the prosthetic knee joint assembly.